With development of electronic technology, light-emitting diode (LED) is widely used in application of general illumination market and display market per smaller, easier driver and higher efficiency. Currently, LED driver system typically uses a three-stage circuit structure. A precise current is needed for LED driving, and other voltage power supplies, for example, 12V and/or 5V, are also needed for powering other circuits of LED driver system.
There are several kinds of structures for LED driver system, for example, multi-stage LED driver system with voltage converters and LED driver circuit. As shown in FIG. 1, a conventional three-stage LED driver system 100 comprises a power factor correction (PFC) stage 11, an isolated DC/DC converter stage 12, an isolated DC/DC converter stage 13, and a LED driver stage 14. Isolated DC/DC converter 13 is used to provide DC voltage power supplies, 12V and 5V. Isolated DC/DC converter 12 is used to provide power for LED driver stage 14. LED driver stage 14 is used to drive a LED Panel. It is obviously that conventional three-stage LED driver system 100 is complex, low efficiency and has high cost and large size.